When the priests and Levites from Jerusalem ask John the Baptist, "Who are you?," he is pretty sure of who he is. He is just a prophetic voice that does God's bidding. Besides that, he is also pretty sure of why he is doing what he is doing - proclaiming and baptising. He is not the Christ.

The writer of 1 John is encouraging his followers to know who they are, so that they are not led astray by those who are liars and anti-Christ. The followers of Jesus are the anointed ones. They have been anointed with truth, and not with a lie. They are asked to keep alive what they have been taught from the beginning. Furthermore, they are asked to live in Christ.

We also have been anointed at our baptism and confirmation. We are children of God. We have the truth. We are pretty sure of who we are. Therefore, we can hold steadfast to our faith, and not be easily led astray by those who claim they have life and truth. These are liars and anti-Christ. But we have Christ with us and in us. We have hope in Christ. "Live in Christ, then, my children, so that if He appears, we may have full confidence, and not turn from Him in shame at His coming." (1 Jn 2:28)